Burner control system



BURNER CONTROL SYSTEM Filed Feb. 2, 1945 3maentor:

WILLIAM A. QAY,

(Ittorneg.

Patented Dec. 4, 1945 BURNER CONTROL SYSTEM William A. Ray, Los Angeles, Calif., assignor to General Controls Co., a corporation Application February '2, 1945, Serial No. 575,869

7 Claims. (Cl. 158117.1)

My present invention relates to means for controlling the operation of a fluid-fuel burner system of the type which includes a main burner, a pilot burner for themain burner, an electric igniter for the pilot burner, and an electrically operated valve for controlling supply of fuel to the main burner. 4

An object of this invention is to provide, in a system of the character described, means responsive to the extinction of the pilot-burner flame for rendering the system completely inoperative so that not only is flow of fuel to the main burner and the pilot burner then obstructed, but also the igniting means is inactivated.

Another object is to provide, for initiating operation of the system, a singly manual-reset means for temporarily passing fuel to the pilot burner and for energizing the igniting means.

Another object is to provide means, responsive to the flame established at the pilot burner as a result of the aforementioned initial operation of the system, for conditioning the mainburner valve for opening and for maintaining flow of fuel to the pilot burner.

Another object is to provide, in combination with the means recited in the preceding objects, a motor operated by the pressure of the fuel in the system and so constructed that its movements are relatively slow.

Another object is to provide means :tor preventing reestablishment of the igniting circuit except by actuation of the resetting means, and then only after a predetermined interval following extinction of the pilot-burner flame.

Other objects and advantages of the invention will be found in the description, the drawing, and the claims; and, for full understanding of the invention, reference is to be had to the following detailed description and accompanyingv drawing, the single figure of which is a view, mainly in diagram, of a gas-bumer control system embodying the invention.

In the drawing, the numeral N indicates a conduit through which gas froma source (not shown) is supplied to a main burner l2 under the control of an electromagnetically operated main valve l3. Branching from conduit al ead of the main valve I3, is a pipe I4, which leads to the inlet l5 of a combination fluid-pressure-operated switch and pilot-burner valve generally indicated at It; the outlet ll of device |6 being connected by a pipe |8 to a pilot burner IQ for igniting the main burner |2. The device I3 comprises a pair of hollow casing sections 2|! and 2| between which is clamped at its margin a main flexible diaphragm 22. The open bottom end of the lower section 2| is closed by another flexible diaphragm 23 to form a pressure chamber 24, below the main diaphragm 22, constantly subjected to the source pressure; another pressure chamber 25, above the main diaphragm, being formed by the upper section 20,

the apertured top end of which is closed by a housing 23. Controlling fluid pressure in the upper chamber 25 is a three-way pilot valve comprising a pair of Jets 28 and 29 with which a movable blade-like closure 30 cooperates. The jet 28 is fitted in a horizontal passage 3| in the upper section 20, which passage is in communication with the lower pressure chamber 24 through a vertical passage 32 in member 20 which registers with an L-shaped passage 33 in section 2|. Cooperating with a reduced section 34 of passage 3| is a conically-pointed screw 35 whereby the rate of flow of gas to the jet 23 can be adjusted. The jet 29 fits in another horizontal passage 33 which leads through a pipe 31, in series with a flow-restricting member 38 to the atmosphere; the pipe 31, in practice, being extended to a point adjacent the main burner 12.

The pilot closure 30 is of magnetizable material and is fulcrumed on the lower arm of a U-shaped electromagnet? core 39 mounted on the top surface 01 section 20; a compression spring 40 biasing the closure-armature 30 away from theupper arm of the core and into engagement with jet 23. Around the upper arm of core 39 is an energizing coil 4| which is connected by wires 42, sealingly and insulatingly extending through the top wall of housing 25, to a thermoelectric generating device generally indicated at 43 and comprising one or more thermocouples, contained within a shell 44, having hot junctions adapted to be heated by the flame 45 of pilot burner l9.

Connected, by a link 43, to stifiening plates arranged on opposite sides of the main' diaphragm 22 is a bell-crank 41 which is secured to a member 48 with a portion of diaphragm 23 therebetween; member 48 being rockably mounted on a pin 49 secured to a housing 50 which is,

attached to the lower section 2| below diaphragm 23. Pivotally mounted by its slotted left-hand end on the upper portion of bell-crank 41 is an auxiliary closure member 5| having at its righthand end a conical head cooperable with the mouth of the outlet passage l1. Carried by mem. ber 48 is a switch arm 52 which cooperates with a pair of resilient contact blades 53 and 54 insulatingly mounted on housing 50.

With the parts in the positions shown in the drawing, both of the chambers 24 and 25 are equally subjected to the pressure of the fuel since jet 28 is open and jet 29 closed, diaphragm 22 therefore being in its depressed position to which it is biased mainly by the weight of its stiffening plates; Downward movement of diaphragm 22 is limited by engagement of auxiliary closure 5| with its seat so that the contact arm 52, carried by member 48, is out of engagement with both of the contact blades 53 and 54.

The switching means, constituted by contact arm 52 and blades 53 and 54, serves to selectively control energization of two electrical circuits. When the contact arm is in engagement with the lower blade 54 a first circuit is completed which comprises the secondary 55 of a conventional A. C. service transformer 56, a thermal cut-out 51, the primary 58 of an ignition transformer 59, and a switch 60 operated by the main-burner valve l3; the circuit being traced from the righthand side of the transformer secondary 55,

through wire BI and flexible extension 52, switch side of secondary 55. When the switch arm 52 is in engagement with the upper contact blade 53, a second circuit is completed which comprises a thermostat I (located, it is to be assumed, in a space heated by the main burner), the electrically operated valve l3, and transformer secondary 55; this circuit being traced from the righthand side of secondary 55 through wire 6| and flexible extension 52, contact arm 52, blade 53, wire H, thermostat I0, wire 12, energizing coil 13 of solenoid valve l3, wire 14, thermal cut-out contacts 58, and wire 59 back to the other side of secondary 55. The secondary 15 of ignition transformer 59 is connected by wires 15 to a heating coil 11 for igniting gas at the pilot burner |9.

To initiate operation of the system, the first or igniting circuit is temporarily completed by actuation of a reset button or stem 18 reciprocable in a flanged opening through the bottom wall of housing 50. When this stem is manually moved upwardly, against the force of its bias spring 19, the inner end of the stem engages the contact blade 54 and flexes it into contact with arm 52, continued movement of the reset stem moving arm 52 upwardly so that the member 48 and bell-crank 41 are rocked slightly in a counterclockv'vise direction, thereby unseating the auxiliary closure member and permitting gas to pass from chamber 24 to the pilot burner. Since by engagement of blade 54 with arm 52 the inition transformer 59 is energized, the coil 11 soon becomes heated to a degree sufllcient to ignite the gas issuing from the pilot burner. The flange 85 surrounding reset stem 18 so limits upward movement of the stem that movement thereby of switch arm 52 into engagement with the upper contact blade 53 is prevented. The reset stem is manually retained in its raised position until the thermoelectric generating device 43 becomes heated to a degree such that electricity is thereby generated in an amount sufficient to so energize the core 39 that the armature-closure 30 is attracted out of engagement with jet 29 and into engagement with the other jet 28. When this occurs, the gas compressed in the upper chamber 25 is slowly vented to the atmosphere through moved to a somewhat inore fully open position in this movement of the main diaphragm, The reset stem may then be released.

Since the second circuit is completed through contact blade 53, if the thermostat 10 is in circuit-closing condition the closure 8| of valve 3 is raised and gas then passes to the main burner where it is ignited by the flame of the pilot burner. While flame exists at the pilot burner the main diaphragm 22 of device I6 is maintained in its raised position wherein the second" circuit is completed and the auxiliary closure 5| maintained in open position; the main-burner valve |3 then being opened and closed in accordance with the demand of thermostat 10 or any similar device which may conveniently be employed for controlling the sec0nd" circuit.

Inthe event of accidental extinction of the pilot-burner flame, upon resultant cooling of thermoelectric generating device 43 the electromagnet core 39 is deenergized so that the armature-closure 30 is released and assumes the position shown in the drawing. Gas can then pass through the open jet 28 into chamber 25 and, since this chamber is now closed with respect to the atmosphere, the fluid pressure therein gradually becomes the same as that in chamber 24 below the main diaphragm so that that diaphragm falls under the force of gravity and the switch arm 52 is disengaged from contact blade 53, thereby completely deenergizing the system. It is thus seen that in response to extinction of the pilot burner flame, not only is passage of fuel to the main and the pilot burnerobstructed but also the igniting means is rendered inactive,

-so that the attention of an operator is required to reinitiate operation of the system by actuation of the resetting means I8; the system therefore being rendered completely safe if the pilot burner'is extinguished.

Due to the flow restriction 34, the downward movement of the main diaphragm is relatively slow so that there is an appreciable lapse of time after arm 52 is disengaged from blade 53 before this arm is again in position to complete (under the control of reset stem 13) the first or igniting circuit. There is therefore very little probability of explosion of gas which may have passed unburned from the main burner, after extinction of the pilot-burner flame, into the space or furnace wherein the burners may be enclosed.

The energization and deenergization of the electromagnet core 33,1sufiicieht to attract or release the armature-closure 30, may be either relatively rapid or slow depending upon the'particular construction of the elements of the thermoelectric generating device; and the rate of rise of the main diaphragm 22 in response to energization of the electromagnet is governed by the flow capacity of the restriction 38.

In the opening movement of the main-burner valve l3 the arm 34 of switch 50 is moved" (by an extension 32 of the solenoid plunger) out of engagement with contact 65 so thatthe igniting circuit is additionally interrupted at this point, thereby preventing the possibility of completing the igniting circuit while the main-burner valve the switching means and the auxiliary valve; a

tional construction and is operated to.- contactopening position only in the event of failure of ignition due to a defect in the transformer 88 or heating coil 11, or in the event that the proper amount of gas fails to issue from the pilot burner when the auxiliary closure BI is opened. It will be observed that the thermal cut-out contacts 88 control both the flrst" and the "second circuits.

The embodiment of my invention herein shown and described is obviously susceptible of modification without departing from the spirit of the invention, and I intend therefore to be limited valve in said second circuit for controlling supply I of fuel to said main burner, and biased to closed position; switching means for controlling a source of electrical energy and adapted to connect said circuits individually to the source; an auxiliary valve for controlling supplyof fuel to said pilot burner; manual means for temporarily operating said switching means to first-circuitconnecting position and said auxiliary valve simultaneously to open position; and means responsive to the flame of the pilot burner, and operated after a predetermined interval following the establishment of said flame, for operating the switching means to second-circuit-connecting position and for maintaining the auxiliary valve in said open position. I

2. In a' gas-burner control system: a main burner; a pilot burner for said burner; a first electrical circuit; electricalmeans in said first circuit for igniting fuel at said pilot burner; a second electrical circuit; an electrically operated valve in said second circuit for controlling supply of fuel to said main burner, and biased to closed position; switching means for controlling a source of electrical energy and adapted to connect said circuits individually to the source; an auxiliary valve for controlling supply of fuel to said pilot burner; manual means for temporarily operating said switching means to flrst-circuit-connecting position and said auxiliary valve simultaneously to open position; a motor, operable by the pressure of the fuel, for operating the switching means and the auxiliary valve; and means responsive to the flame of the pilot burner for so controlling said motor that, after a predetermined interval following establishment of the flame, the switching means is operated to second-circuit-connecting position and the auxiliary valve is maintained in said open position,

3. In a gas-burner control system: a main burner; a pilot burner for said main burner; a first electrical circuit; electrical means in said first circuit for igniting fuel at said pilot burner; a second electrical circuit; an electrically operated valve in said second circuit for controlling supply of fuel to said main burner, and biased to closed position; switching means for controlling a source of electrical energy and adapted to connect said circuits individually to the source; an auxiliary valve for; controlling supply of fuel to said pilot burner; manual means for temporarily operating said switching means to firstcircuit-connecting position and said auxiliary valve simultaneously to open position; a motor,

operable by the pressure of the fuel, for operating pilot valve for controlling operation of said motor; and means, responsive to the flame of the pilot burner, effective only after a predetermined interval following'stablishment of the flame to.

so operate said pilot valve that the switching means is operated to second-circuit-connecting position and the auxillary'valve is maintained in said open position.

4. In a gas-burner control system: a. main burner; a pilot burner for said main burner; a first electrical circuit; electrical means in said first circuit for igniting fuel at said pilot burner;

a second electrical circuit; an electrically operated valve in said second circuit for controlling supply of fuel to said main burner, and biased to .closed position; switching means for controlling a source of electrical energy and adapted to connect said circuits individually to the source; an auxiliary valve for controlling supply of fuel to said pilot burner; manual means for temporarily operating said switching means to first-circuit-connecting position and said auxiliary valve simultaneously to open position; a motor, operable by the pressure of the fuel, for operating the switching means and the auxiliary valve; a pilot valve for controlling operation of said motor; means responsive to the flame of the pilot burner for so operating said pilot valve that, upon establishment of the flame, the switching means is operated to second-circuit-connecting position and the auxiliary valve is maintained in said open position;

' and means associated with said motor for so restricting flow of fuel with respect thereto that operation of the switching means and the aux- I iliary valve is delayed for a predetermined in terval following establishment of the flame.

5. In a gas-burner control system: a main burner; a pilot burner for said main burner; a first electrical circuit; electrical means in said first circuit for igniting fuel at said pilot burner; a second electrical circuit; an electrically operated valve in said second circuit for controlling supply of fuel to said main burner, and biased to closed position; switching means for controlling a source of electrical energy and adapted to connect said circuits individually to the source; an auxiliary valve for controlling supply of fuel to said pilot burner; manual means for temporarily operating said switching means to first-circuitconnecting position and said auxiliary valve simultaneously to open position; a motor for operating the switching means and the auxiliary valve, and comprisingvmeans forming a pair of pressure chambers separated by a movable partiing means is operated to second-circuit-connecting position and the auxiliary'valve is maintained in said open position; and means responsive to the flame of the pilot burner for operatlng said pi: at valve.

6. A system, as defined in claim 5, including means for so restricting flow of fuel with respect to said one of the motor chambers that operation of the switching means and auxiliary valve is delayed for a predetermined interval following establishment of the flame.

7. In a gas-burner control system: a main burner; a pilot burner for said main burner; a

operable by the pressure of the fuel, for operating the switching means and the auxiliary valve; 1;. pilot valve for controlling operation 01 said motor; an electromagnetic device for operating said pilot valve; and a thermoelectric generating device, arranged for heating'by the flame oi? the pilot burner, for energizing said electromagnetic device, the thermoelectric generating device being so constructed that it heats relatively slowly so that operation oi the pilot valve is delayed for a predetermined interval following establishment of the flame.

' WILLIAM APRAY. 

